Predictive factors for the development of central line-associated bloodstream infection due to gram-negative bacteria in intensive care unit patients after surgery

OBJECTIVES: To examine the relative proportions of central line-associated bloodstream infection (BSI) due to gram-negative bacteria and due to gram-positive bacteria among patients who had undergone surgery and patients who had not. The study also evaluated clinical predictive factors and unadjusted outcomes associated with central line-associated BSI caused by gram-negative bacteria in the postoperative period. DESIGN: Observational, case-control study based on a retrospective review of medical records. SETTING: University of Chicago Medical Center, a 500-bed tertiary care center located on Chicago's south side. PATIENTS: Adult intensive care unit (ICU) patients who developed central line-associated BSI. RESULTS: There were a total of 142 adult patients who met the Centers for Disease Control and Prevention National Nosocomial Infection Surveillance System definition for central line-associated BSI. Of those, 66 patients (46.5%) had infections due to gram-positive bacteria, 49 patients (34.5%) had infections due to gram-negative bacteria, 23 patients (16.2%) had infections due to yeast, and 4 patients (2.8%) had mixed infections. Patients who underwent surgery were more likely to develop central line-associated BSI due to gram-negative bacteria within 28 days of the surgery, compared with patients who had not had surgery recently (57.6% vs 27.3%; P= .002). On multivariable logistic regression analysis, diabetes mellitus (adjusted odds ratio OR], 4.6 95% CI, 1.2-18.1]; P= .03) and the presence of hypotension at the time of the first blood culture positive for a pathogen (adjusted OR, 9.8 95% CI, 2.5-39.1]; P= .001) were found to be independently predictive of central line-associated BSI caused by gram-negative bacteria. Unadjusted outcomes were not different in the group with BSI due to gram-negative pathogens, compared to the group with BSI due to gram-positive pathogens. CONCLUSIONS: Clinicians caring for critically ill patients after surgery should be especially concerned about the possibility of central line-associated BSI caused by gram-negative pathogens. The presence of diabetes and hypotension appear to be significant associated factors.